1. Field of the Invention
The present invention relates to a remote sensing apparatus for transmitting laser light toward a rotary plate with an optical pattern formed thereon (hereinafter, referred to as optical pattern rotary plate) and convert a signal which is reflection light of the laser light and received by an optical receiver into a frequency domain to perform frequency analysis of the signal.
2. Description of the Related Art
A remote sensing apparatus represented by a conventional laser radar irradiates laser light toward an optical pattern rotary plate being a measurement object to receive reflection light from the object, converts the reception signal into a signal in a frequency domain to perform frequency analysis, then extracts characteristic information of the object (for example, refer to Japan Patent Application Publication [KOKAI] No. 2005-037206). As for its frequency analytical method, a frequency having maximum vibration amplitude in a carrier frequency domain is determined as a carrier frequency candidate value if the reflection light is frequency modulated (FM) by an optical pattern of the object. The carrier frequency candidate value is obtained through the use of a fact that a difference between a carrier frequency and a sideband wave frequency is equal to a rotational frequency. However, this analysis method sometimes cannot correctly select the carrier frequency candidate value when the carrier frequency does not become a maximum value.